This invention relates to reactive dyestuff compositions for cellulose fibers and to a method of dyeing the cellulose fibers by using the reactive dyestuff compositions.
Textile materials having free OH groups such as cellulose, having NH groups such as sheep wool and silk, and materials containing carbonamide groups can be dyed into all color tones or hues by using reactive dyestuffs on the present level of the technique of this field. Formation of a covalent bond between the dyestuff and the textile material provides a high fastness property of these dyeings. The reactive dyestuff is frequently applied to the textile material from an aqueous dyeing bath in accordance with the exhaust method. The temperature for the dyeing method is in most cases 40.degree. to 90.degree. C.
The dyeing result of the reactive dyestuff is dependent on the substantivity of the reactive dyestuff, that is, the dyeability, on the diffusion and the migration, and on the reactivity of the reactive group with the textile material, which are remarkably affected by the dyeing parameters, that is, the temperature of dyeing, the content of electrolytes in a dye liquor, the pH value of the dye liquor and so on. Therefore, in order to obtain an optimal dye concentration and a good leveling property, the reactive dyestuff must be used for dyeing in a narrow limited range of the temperature with the addition of the proper electrolytes and alkalis.
Furthermore, the dyeing result of the reactive dyestuff is dependent on the used amount of the dye liquor for the textile material, so-called bath ratio.
From these facts, it has been thought that a different dyestuff requires a different dyeing method for the optimum use.
In practice, it has been generally carried out that the reactive dyestuffs are used as a mixture of two or three, or, in a rare case, more reactive dyestuff components in order to obtain a constant color tone. In particular, it is preferably carried out to use a trichromatic combination (Trichromie). In this case, most of all possible color tone can be obtained by mixing clear yellow with red and brilliant blue in a suitable mixing ratio. The reactive dyestuffs in the respective colors to be used for such combination dyeing should have similar dyeing properties, that is, the combination dyeing should not be varied by the influence of dyeing parameters such as the temperature, the addition of the electrolytes and the bath ratio. Accordingly, it is required for the reactive dyestuff compositions to dye without substantially being influenced with the dyeing temperature, the addition of the salts and the bath ratio.
For example, West German patent publication No. 2,442,553, European patent application Nos. 209,494 and 198,198 disclose the examples of mixing of the reactive dyestuffs. The objects of the mixtures disclosed in the above references are however to improve the solubility of the dyestuffs in water or the exhaustion property of the dyestuffs so as to make it possible to produce the dye liquor which gives a sufficient concentration. Furthermore, European patent application No. 44,483 discloses only that the mixture of at least two red azo reactive dyestuffs which dye in the same color tone has less sensitivity to the change of dyeing parameters.
The combination of reactive dyestuffs is carried out not only in case of the reactive dyestuffs having only one reactive group in a molecule of the dyestuff but also in case of the reactive dyestuffs having two or more reactive groups in a molecule. That is, it is carried out to mix three kinds of reactive dyestuffs of yellow, red and blue which have, for example, both a .beta.-sulfatoethyl-sulfonyl group and a triazine group (it is not referred to herein that the latter is halogenated or not.) in a molecule to obtain various color tones.
However, a few kinds of the reactive dyestuffs, in particular, the two-functional dyestuffs to be actually industrially used prevent us from obtaining a variety of color tones.